Aluminium-aluminium nitride composites fabricated by melt infiltration under pressure

Aluminium-matrix composites containing similar to 55 vol.% AlN particles we re fabricated by melt infiltration of aluminium into an AlN preform under a pressure of up to 130 MPa. Two different AlN powders (H.C. Starck, Goslar, Germany, and ESK, Elektroschmelzwerk, Kempten, Germany) and four types of aluminium alloy (2024, 1070, 6060 and 5754) were used, The initial AlN powd ers were characterized by scanning electron microscopy. The composites were studied by light microscopy, scanning and transmission electron microscopi es and energy-dispersive X-ray spectroscopy. Particle-matrix interfaces wer e observed using high-resolution electron microscopy. As a result of the me lt infiltration process, the composites are very dense and the microstructu re shows a homogeneous distribution of the reinforcement. The interfaces ar e clean with very little porosity. Some Al2Cu precipitates were observed in the 2024 matrix.